(a) Field of the Invention
The present invention relates to a method for assembling an inner core/cylinder block assembly for a linear compressor.
(b) Description of the Related Art
In general, a linear compressor is used in a refrigeration system that provides refrigeration energy by undergoing a refrigerant the successive process of compressing, condensing, expanding and evaporating. The linear compressor has a linear motor, which is driven by electromagnetic force created by the alternate direction change of magnetic flux, to compress the refrigerant at high temperature and pressure.
FIG. 1 shows a conventional linear compressor, and FIG. 2 shows an inner core of the conventional linear compressor.
As shown in the drawings, the conventional linear compressor comprises an airtight container 10, a driving part generating a driving force in the airtight container 10, and a compressing part inhaling, compressing and discharging a refrigerant by using the driving force of the driving part.
The compressing part comprises a piston 11 and a cylinder block 13 provided with a compressing chamber 12 in which the piston 11 is slidably disposed. On one end of the cylinder block 13 is mounted a cylinder head 16 in which an inhaling chamber 14 and a discharging chamber 15 are provided for guiding the refrigerant to the inside and outside of the compressing chamber 12, respectively.
The driving part comprises an inner core 20 coupled on an outer surface of the cylinder block 13, a stator 30 spaced away from the inner core 20 at a predetermined distance, a permanent magnet 22 disposed between the inner core 20 and the stator 30 to interact with an electric field formed by the stator 30.
The stator 30 includes a cylindrical bobbin 31, coils 32 wound around the bobbin 31, and outer core 33 inserted into the bobbin 31.
On the lower end of the piston 11 is provided a fixing shaft 11a with a frame 40 for fixing the permanent magnet 22. A resonant spring 41 for elastically supporting the piston 11 is connected to the lower end of the fixing shaft 11a to raise compressing force of the piston 11.
The inner core 20 is made by piling up rectangular-shaped electric steel plates 21 and is arranged radially along the outer circumference of the cylinder block 13. Korean laid-open patent No. 96-39553 discloses a method for piling the steel plates 21 and assembling the inner core 20 and the cylinder block 13. This will be described hereinafter with reference to FIG. 2.
Each steel plate is first magnetized by a magnetic flux generating device (not shown), then the magnetized steel plates 21 are radially disposed about a holder 50.
The holder 50 includes a cylindrical main body 51, an inner extending portion 52 extending inwardly at the lower end of the main body 51, and an outer extending portion 53 extending outwardly at the lower end of the main body 51. The inner extending portion 52 is provided with a plurality of screw holes 52a so that the holder 50 can be coupled on the lower end of the cylinder block 13 by a screw 54. Each magnetized steel plate 21 is disposed on the outer extending portion 53.
The magnetized steel plates 21 disposed on the holder 50 are fixed by an adhesive, thereby obtaining a radially piled inner core 20. And, the holder 50 is coupled to the cylinder block 13 by screw-coupling the screws 54 through the screw holes 52a, thereby completing the coupling process of the holder 50 to the cylinder block 13.
However, in the conventional compressor, to dispose the steel plate 21 on the holder 50, a special magnetic flux generating device is required, making the manufacturing process complicated. In addition, since the steel plates 21 are attached on the holder 50 by an adhesive, the same may be easily removed by external force, deteriorating the performance of the compressor. Furthermore, to assemble the inner core 20 on the cylinder block 13, additional fastening members such as the holder 50 and the screws 54 are required, lowering the productivity and increasing the manufacturing costs.
The present invention has been made in an effort to solve the above problems.
It is an objective of the present invention to provide a method for manufacturing a linear compressor easily and with the low costs.
To achieve the above objective, the present invention provides a linear compressor comprising a cylinder block in which a compressing chamber is formed; and an inner core having a plurality of electric steel plates disposed around the cylinder block, wherein the cylinder block extends into spaces between the electric steel plates so that the cylinder block is integrally formed with the inner core.
Each of the electric steel plates comprises an insertion projection extending from a surface toward the cylinder block and an insertion step extending upward and downward from the insertion projection to form a concave between the surface and the insertion step, the cylinder block extending into the concave to interlock with the inner core.
According to another aspect of the present invention, a method for manufacturing the linear compressor comprising the steps of punching each of the electric steel plates; radially stacking the electric steel plates; welding the electric steel plates to form the inner core; inserting the inner core into a cast mold for casting the cylinder block; pouring molten material into the cast mold and applying pressure to the cast mold so that the molten material is filled into spaces between the electric steel plates, thereby making the inner core integral with the cylinder block.
The punching step further comprises the steps of forming an insertion projection on a surface of the electric steel plate; and forming an insertion step on the insertion projection. The stacking step further comprises the steps of preparing a jig having an insertion groove; and stacking the electric steel plates along the jig in a semi-cylindrical shape by inserting the insertion step into the insertion groove.
The welding step further comprises the step of welding the electric steel plates along the insertion steps. The method further comprises the step of making a pair of inner cores inserted into the cast mold.
The punching step further comprises the steps of forming an insertion projection on a surface of the electric steel plate and forming an insertion step on the insertion projection to form a concave between the insertion step and the surface.
The molten material is filled into the concave during the pouring step.